Structure of thinned continental crust across the Orphan Basin from a dense wide-angle seismic profile and gravity data
Notice bibliographique
Résumé
We present a 500-km long, 2-D P-wave velocity model across the Orphan Basin, offshore NE Newfoundland, Canada, from Flemish Cap to the Bonavista Platform, formed using refraction and wide-angle reflection data from 89 ocean-bottom seismometers. This layered model builds on a recent traveltime tomography result using additional constraints from coincident multichannel seismic reflection and gravity data plus borehole logs from three wells. The model shows (i) post-rift Tertiary (velocities ∼1.7–3.5 km s−1) and (ii) both post-rift and syn-rift, Cretaceous and Jurassic sediments (∼4–5 km s−1), deposited within an eastern and a western sub-basin that are separated by a major basement block. The existence of Jurassic sediments indicates a pre-Cretaceous rifting phase in the eastern sub-basin, and possibly in the western sub-basin. However, there is no evidence that Triassic sediments are widespread across the Orphan Basin. Two upper crustal sublayers and one lower crustal layer are defined by differences in velocities (5.4–6.1, 6.1–6.5 and 6.3–7.1 km s−1, respectively) and vertical velocity gradients (mean = 0.14, 0.10 and 0.05 s−1, respectively). Crustal thinning is asymmetric across the Orphan Basin. Within the eastern sub-basin, continental crust beneath Flemish Cap (∼32 km thick; β ∼ 1.1) thins westward into a 35-km-wide zone of hyperextended crust (<10 km thick; β > 3.4) beneath an 11-km-deep sedimentary basin. Within the western sub-basin, the Bonavista Platform crust (∼32 km thick) thins eastward into a 116-km-wide zone of hyperextended crust. Two zones of thicker crust (β = 2–3.5) exist within the central section, with muted topography within the eastern part and large basement highs in the western part, separated by the eastward dipping White Sail Fault (WSF). The zone to the east of the WSF displays higher velocities in the lower crust than to the west. This can only be explained by a lateral ductile flow across the zone boundary. By combining the two upper crustal sublayers into one, we define the full crustal thicknesses of the upper and lower crusts as 12 and 22 km, respectively. The extension and thinning factors of these two layers are calculated across the basin. Discrepancies between upper crustal thinning and lower crustal thinning are common but only produce a small mass deficit (∼7 per cent or 1.5 km) in the lower crust. Structural connections are shown between the Rockall Trough and the West Orphan Basin and between the Porcupine Basin and the East Orphan Basin in that a wider hyperextended western basin is paired with a narrower eastern basin by a middle zone of thicker crust. In contrast to the Rockall Trough and the Porcupine Basin, serpentinized mantle is not observed in the East Orphan Basin where hyperextended crust is observed (βmax ∼ 8.5). One possible cause is that the restricted size of the basin and its location adjacent to Flemish Cap may have permitted a heavier supply of sediment to cover the basement early during its extension. Such a cover would inhibit the flow of water into the crust and thus leave the mantle unchanged.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».